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Potential Applications of Single Source Dual-Energy MDCT in the Diagnosis of Cancer

Explore the potential applications of Single-Source Dual-Energy MDCT in cancer diagnosis, addressing current limitations in tumor detection and assessment. Dual-energy imaging principles, benefits over conventional CT, and novel probabilistic separation techniques are discussed. Preliminary tests demonstrate improved separation and contrast, aiding in early cancer detection and treatment monitoring.

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Potential Applications of Single Source Dual-Energy MDCT in the Diagnosis of Cancer

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  1. AFIIM 2008 PARIS Potential Applications of Single Source Dual-Energy MDCT in the Diagnosis of Cancer Jacob Sosna, MD Department of Radiology Hadassah Hebrew University Medical Center, Jerusalem, Israel Harvard Medical School, Boston, MA

  2. The radiological community in Israel has been involved in CT development since its early days 1975 – Elscint CT founded 1978 – 1st commercial scanner 1979 - High resolution CT 1992 – 1st spiral scanner (CT Twin)

  3. Br iCT 128 channels, 256 slices, 0.27s Br 64-Slice Br 40-slice 1st 16-slice 0.42 sec CT 1st 4-slice 0.5 sec CT World’s smallest whole-body CT Gated multiphase cardiac imaging Isotropic resolution 2x0.5mm 1st spiral (dual slice) scanner(CT Twin) XRT DFS technology Highest resolution (13 lp/cm) 1st Elscint CT (905 scanner) Elscint CT founded 2007 2005 2003 2001 1998 1995 1995 1994 1992 1986 1979 1978 1975 Beta sites in Israeli Radiology Departments Haifa Plant – CT History

  4. Cardiac CT Revolution Cardiac CT scanners iCT Br-64 Br-40 IDT 16 slice Quad Dual Development of subsequent CT scanners was largely driven by the prerequisites for cardiac imaging: iCT Faster scans Greater coverage Increased spatial and temporal resolution Br-64 Br-40 IDT 16 slice

  5. MDCT WHAT IS MISSING?

  6. Are we really good at? • Separation between calcification and Iodine in CTA • Bone-removal in CTA (Cage Removal, Skull Removal etc.) • Soft plaque separation • Bone mineral & bone density assessment • Low contrast resolution (soft tissues) • Tracking drug delivery

  7. Are we really good at? • Early detection of cancer • Reliable measurements of tumors in a reproducible way • Still need for high dose of contrast in repetitive manner • Drug tracking • Tumor vascular studies- e.g. perfusion

  8. Think Outside the Box

  9. DUAL ENERGYImaging CT

  10. But different elements can have same CT #…!! CT today …It’s all about Hounsfield units ( HU or CT# )

  11. Pre-patient Beam filtration Low-Energy X-ray radiation High-Energy X-ray radiation Spectrum Decomposition Principle Intensity KV

  12. Dual-Energy Imaging • Dual-energy imaging takes advantage of differences in the degree to which body tissues attenuate low- and high-energy photons • These differences are used to generate tissue-selective images

  13. Dual Energy Imaging • Two types of dual-energy systems • Single-exposure system • Two detection systems one above the other • Dual-exposure system • Two sequential images are obtained at 2 energy levels with a subsecond delay between the two exposures • This can create misregistration artifacts due to slight offsets in the alignment of body structures caused by cardiac, respiratory, bowel, and patient motion

  14. Simultaneous Multi-Energy Detector (SMED) X-Rays Photons 100% ~50% SCINT1 Low Energy Raw data E1 image + ~50% Double-Deck Diode SCINT2 High Energy Raw data E2 image ---------------------------------------- = Weighted combined Raw data CT image

  15. Combined Inner Outer Non-enhanced

  16. Inner Combined Outer Enhanced

  17. It’s All About the PIXEL -106/-135 -986/1003 +23/+35 +119/147 +197/236 +329/389 +191/215

  18. Main Pathways The SC Benefits over conventional 64 MDCT • Separation • Contrast

  19. Main Pathways The SC Benefits over conventional 64 MDCT • Separation • Contrast

  20. Preliminary Phantom Tests 140 kV, 400 mAs Iodine Iodine Calcification pins of various concentrations and radii Calcium pins ~250 HU at 120 kV Saline

  21. 2D histogram separation

  22. Ca-I Differentiation – Calcified Aneurysm

  23. Iodine OR Calcium Images • Single click bone detection/ removal • Virtual angiography • Virtually cleansed bowel in CTC (iodine/ barium/fat) • Major benefit in CRC screening • Virtual Non enhanced CT

  24. Probabilistic Separation of Iodine:VNC Imaging

  25. E1 (HU) E1 E2 (HU) E2 Non-Binary Probabilistic Separation Defining a model that generate the noisy data (Instead of defining separation line) For each voxel build a Probabilistic Mixture Model over the neighbor in the E1-E2 plane and over the volume neighbor. For each voxel we can calculate the probability to be calcium and probability to be iodine.

  26. Probabilistic Separation The color intensity is proportional to the probability

  27. Purpose To evaluate the ability to generate virtually non enhanced CT images from enhanced clinical CT studies and to compare image parameters to regular non-enhanced and contrast enhanced CT

  28. Materials and Methods • Spectral separation • Enhanced phase (C+) • Virtually non enhanced CT using a probabilistic mixture model (VNC) • Regular non-enhanced CT (C-)

  29. Materials and Methods • ROI of various organs and vessels including • Liver • Spleen • Aorta • PV • Muscle • 2 experienced radiologists in consensus assessed the visibility of calcified areas in the infra-renal aorta and artifacts

  30. Results • All 22 VNC studies could be obtained • Average change from C+ to VNC • Aorta -114.12 (SD 1.2) • RA -135.4 (SD 16) • PV -7.6 (SD 2.34) • IVC -1.73 (SD 1.99)

  31. Results • Average change from VNC to C- • Aorta 38.03 (SD 0.6) • RA 37.8 (SD 2.8) • PV 21.8 (SD 1.93) • IVC 12.2 (SD 0.63)

  32. Results • Average change from C+ to VNC for solid tissues • Muscle 0.40HU (SD 0.19) • Liver 3.5HU (SD 1.15) • Spleen 9.2 (SD 3.15)

  33. Results • Average change from VNC to C- for solid tissues • Muscle 3.29HU (SD 0.53) • Liver 5.79HU (SD 0.28) • Spleen 22.2 (SD 1.72)

  34. Results • Total of 213 calcifications in C- • 196 (92%) calcifications visualized in VNC • “Deleted” calcifications were mainly small areas 1-2 mm in size • Specific artifacts • Edge enhancement • Metallic clips diminished

  35. Scan without iodine With iodine

  36. Scan without iodine VNC

  37. Scan without iodine Scan with iodine

  38. Scan without iodine VNC

  39. Scan with iodine Scan without iodine

  40. VNC Scan without iodine

  41. Conclusions • Diagnostic virtually non-enhanced images can be obtained with single source dual energy CT • Iodine is “deleted” mainly from vessels and does not affect solid organs • Majority of calcifications are preserved • It may obviate the need for regular non-enhanced phase in multi-phasic MDCT especially for CTA studies

  42. Potential Applications in Oncology • No need for non –enhanced phase? • Better visualization of nodules • Benefit in adrenal imaging

  43. Materials • Water • Calcium 0.35-0.04gr/ml diluted in water. • IntraLipid 20%-5% diluted in water. • Iodine (Meglumine Ioxitalamate ): 30 – 3mg/ml diluted in saline. • Gadolinium (gadoteric acid): 0.125-0.025mmole/ml diluted in saline • Cis-platinume 1mg/1ml (DOTAREM- Guerbet, France). • Barium Sulfate suspension 0.02-0.08gr/ml diluted in saline • soy bean oil (92%) • Bovine Liver • Chicken breast

  44. Results • Calcium and Gadolinium are on the same separation line • Barium and Iodineare on the same separation line • We are not sensitive to lipids concentrations <20%(shall be further tested) • Cis platinum not detected reliabley • Further interest in drug detection with specific absorption patterns

  45. 5. Calcium Avg 306 4. Barium Avg 488 6. Gadolinium Avg 362 7. Cis Platinum Avg 26.6 3. 20% oil Avg: -16 8. Water Avg 1.3 2, Oil Avg: -102 1. Iodine Avg: 319 CT numbers

  46. 5. Calcium 4. Barium 6. Gadolinium 3. 20% oil 7. Cis Platinum 2, Oil 8. Water 1. Iodine Materials Separation

  47. Main Pathways The SC Benefits over conventional 64 MDCT • Separation • Contrast

  48. Iodine shows higher signal Iodine shows lower signal Attenuation Calcium Iodine solution Tube Attenuation of different materials reduction in tube voltage leads to an increase in attenuation of iodinated contrast material

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